You need a ENB of your choise in order to this plugin. If your system is too weak for
most of the ENBs check out Aliaris ( extreme performance for low end systems -
even those that can barely handle skyrim itself )

First read it, then do it!

Just place the ENBBLOOM.FX file into you skyrim folder where your ENB is located
this should replace the enbbloom file you already have - so make a backup if you 
dont want to lose it!

And thats it!